Optical fiber cables that include several optical fiber micromodules are known. For example, French Patent Application No. FR 2,665,266 and its counterpart U.S. Pat. No. 5,155,789, which is hereby incorporated by reference in its entirety, and French Patent Application No. FR 2,706,218, and its counterpart U.S. Pat. No. 5,671,312, which is hereby incorporated by reference in its entirety, disclose an optical fiber micromodule surrounded by a retaining jacket enclosing several optical fibers.
A micromodule telecommunication cable includes a plurality of optical fibers grouped in micromodules. The micromodules are typically disposed in a central cavity of the cable such that the cable jacket surrounds the micromodules. This central cavity is surrounded by a jacket. A micromodule may contain about 2 to 24 optical fibers enclosed in a thin, flexible retaining jacket. The retaining jackets of the micromodules and the jackets of optical fibers may be colored to facilitate locating the optical fibers within the cable (e.g., during connection operations).
With the development of telecommunications systems with optical fibers to the subscriber, commonly known as Fiber-to-the-Home (FTTH) or Fiber-to-the-Curb (FTTC), it is desirable to produce cables with sufficient capacity to contain numerous optical fibers (e.g., grouped in micromodules). In this regard, such cables should allow an individual access to each micromodule for distribution in a given building. For this purpose, a field technician makes a bypass in the telecommunication cable. At least one aperture or insertion window is made in the outer jacket of the cable in order to access the interior of the cable. Consequently, one or more optical fibers present in one or more micromodule are cut and drawn from the cable through an insertion window to make a connection to a given optical system in a given building.
European Patent Application No. EP 1,052,533 and its counterpart U.S. Pat. No. 6,181,857, which is hereby incorporated by reference in its entirety, describes a method for accessing one or more optical fibers in a cable for bypassing optical fibers toward an optical system. Two cutouts are made in the cable jacket in order to create a first insertion window through which an optical fiber is cut and a second insertion window through which the cut optical fiber is drawn (i.e., bypassed).
U.S. Pat. No. 6,134,363, which is hereby incorporated by reference in its entirety, describes a method for accessing one or more optical fibers freely positioned in a cable. The cable jacket is stripped on either side of peripheral strength members over a given length to create a window for accessing the optical fibers.
U.S. Pat. No. 5,140,751, which is hereby incorporated by reference in its entirety, describes a tool for accessing one or more optical fibers positioned in a tube framed by strength members. The tool has suitable grooves for receiving the tube and the strength members, respectively. A blade then cuts the tube over a given length to create an insertion window for accessing the optical fibers.
The methods and tools described in the aforementioned patent documents, however, do not provide any particular step for protecting the optical fibers or micromodules during the cutting of the bypass insertion windows. In particular, when the filling rate of the central core (i.e., the optical fiber count) is significant, the cutting tool may penetrate the central core and damage optical fibers contained therein.
U.S. Pat. No. 5,093,992, which is hereby incorporated by reference in its entirety, proposes a tool in which the tube containing one or more optical fibers is bent. A blade then cuts the tube along a tangent to the curvature of the tube in a way that prevents optical fibers from being touched by the blade. This tool, however, is complex and unsuitable for a large capacity cable containing several micromodules and having a significant filling rate.
U.S. Patent Application Publication No. 2002/0126968, which is hereby incorporated by reference in its entirety, describes a cutting tool for an optical cable having an outer sheath, a central cavity, and optical waveguides that are surrounded by a tape. The cutting tool cuts through the outer sheath and penetrates into the central cavity.
European Patent Application No. EP 0,822,427 describes a tool for opening the protective tube of an optical fiber cable. The disclosed tool includes a body, a guide, a cutting edge, and a pulley for bending the optical fiber.
There is a need, therefore, for a method for accessing one or more optical fibers in a telecommunication cable in a way that not only avoids the risk of damaging the optical fibers but also is uncomplicated to employ for various kinds of telecommunication cables.